What do cabbages, broccoli and canola have in common?….They are related of course!

Indeed these three crops are themselves distinct but they all are species within the Brassica family of plants. While broccoli and cabbage might be regulars on the dinner plate canola is not, although perhaps in a more oily form. If you are ever lucky enough to grow some brassicas (broccoli, cabbage, bok choy etc.) they’ll all have a very similar and distinct smell!

As a crop, canola is grown for its seed. These tiny seeds are characterized by a high oil content potentially reaching in excess of 40% of seed volume. Oil that is harvested is used in food processing and cooking and is the reason canola fetches such a high price.

Modern canola as we know it is a relatively recent crop having been bred specifically from rapeseed in the 1970’s in Canada, which happens to be a substantial contributor of the annual global canola crop. Primitive ancestors of modern day canola however have been in cultivation for over 2,000 years in India and China.

Fun fact #1: The “can” in canola refers to Canada where it was bred and the “ola” refers to vegetable oils like mazola. 


Canola is an important crop species used in agriculture today. In Australia it is referred to as a cash crop given its high price, one of the reasons most broadacre farmers will include it in their crop rotations.

Canola can be planted and harvested the same as any other cereal or legume crop using the same machinery, albeit slightly tweaked to account for the minute size of the seeds.


Canola is typically sown earlier than other crops to maximize yield potential and to avoid flowering during frost events, which in Western Australia typically occur during early spring. A canola plant is highly branched and can be taller than a person under certain conditions, because of this canola is sown at lower rates per hectare (1.5 – 2.5 kg seed/ha) than other crops (wheat can be up to 80 kg/ha). Seeding rates of GM canola are typically even lower, given the high cost associated with the new technology.

To account for the small size of the seed, the openings that measure the rate of seed delivery must be calibrated and designed with small particle flow in mind. The flow dynamics of canola are very different to wheat!


Often before harvest takes place, when the crop is 8-10 days off maturing, the crop will be swathed. Swathing refers to cutting the crop and placing it in a windrow which helps avoid seed pod shattering if the crop was to be directly harvested and uneven ripening of the pods on each individual plant. Desiccation (drying) of the crop can also be done with broad spectrum herbicides (such as glyphosate or diquat). Similarly to swathing, chemical desiccation improves seed retention and evens the drying of the crop for an improved harvest.

Modifications made to the harvester are critically important in ensuring the hard earned seed doesn’t end up out in the field and not in the silo. The sieves at the back of the harvester figuratively (in the case of canola) sort the wheat from the chaff. If they are left open in the case of wheat or lupin harvesting, canola seed and lots of chaff will fall through and produce a dirty final product. Special sieves with small holes are designed for canola with the aim of improving the cleanliness of the collected seed. The small and lighter grain also means that faster fan speeds will blow it out the back. So farmers slow the fan down.

As harvest progresses farmers will continually monitor seed loss through sensors and field tests of the chaff and straw spread out the back end.


Canola unlike cereals and legumes requires far more macro- and micro-nutrients to grow, this is testament to the high oil content and consequently high energy requirement of that oil production. A canola crop is hungry for nitrogen and particularly sulphur. Growers need to supply more to meet the yield potential and the desired oil content. Often a grower is able to capture a premium price with higher the oil contents.

Canola is an open pollinated crop. Unlike cereal crops (barley or wheat) canola requires transfer of pollen from a different individual to fertilize its ovules which form into the seeds. Pollination is typically carried out by the wonderful bee, but wind and even human interference can assist in pollination. Although bees are generally the dominant pollinators, hence bee hives are often found close to a canola crops to facilitate pollination and maximise yield potential.

Fun fact #2: Honey produced near a canola crop is light in colour and crystallizes very easily compared to some other honey types (e.g. Manuka). 

Genetic Modification

There is much controversy around canola varieties because a larger proportion are become genetically modified. Most of the genetic modification revolves around herbicide tolerance which allows a grower to spray a particular herbicide as the crop is growing, which would otherwise normally kill the crop. This provides an opportunity for controlling in-crop weed species with broad spectrum glyphosate instead of with more toxic and expensive selective herbicides.

Genetic modification has also enabled the development of varieties that produce omega-3 fatty acids normally found in fish oil. This will reduce the need to harvest millions of tonnes of fish for their oil and in turn reduce the burden on ocean ecology.

Globally more and more GM canola is being grown, primarily for weed management, in Australia the hectares allocated to GM canola as opposed to conventionally bred canola is increasing every year as weed burdens rise. Although they are controversial, a recent meta-analysis study found that GM crops reduce the environmental impact of crop production by decreasing certain chemical usage and improving yield potentials.

Fun fact #3: The glyphosate tolerant genes found in Monsanto’s Roundup Ready® canola varieties was isolated from two bacterium species.  

Canola is an important crop for the food industry and is a highly priced and highly researched species. It has come a long way in the past 2,000 odd years and certainly does not resembles its close cousins broccoli or cabbage. If you would like to know more about the production of canola in Australia or its home country Canada follow these links……Australia……Canada.